PURPOSE: To accord an aperture shape with an ion beam shape so as to improve use efficiency of the ion beam by rotating, with an ion beam shaft as the center, a ion source and a drawing electrode at the same time.

CONSTITUTION: An ion source housing 11 is held, in the condition where the rotation is possible with a bearing 12 round an ion beam shaft as the center, by a base 10. For housing 11, a link 13 mounted to the housing 11 is connected to a driving screw 14 and the screw 14 is engaged with a shaft 15a interlocking with a motor 15 and the screw is retreated by the rotation of the motor 15, thus the housing 11 fixed with a drawing electrode 17 at the front of the ion source 16 is rotated normally or reversely with a beam shaft as the center. In operation, after starting the operation of the ion source 16, various kinds of adjustments are executed and further the angle of the ion source housing 11 is rotated into the position where the shape of each part aperture where an ion beam b passes through agree with that of the ion beam.